1. Field of the Invention
The present invention relates to an electrical connectors or terminals. In particular, the present invention relates to such electrical connectors having a contact element and a spring element, the contact element having a contact zone formed by two contact legs, and a bent spring area which connects the contact legs to the contact zone that apply a contact force to a mating contact element inserted into the contact zone, where the spring element has two legs and a bridge which connects the legs.
2. Description of the Related Art
Electrical connectors or terminals are used to produce an electrically conductive, preferably metallic, connection between a contact element, and a mating contact element. Whether in the specific application there is an electrical terminal or an electrical connection is functionally relatively trivial. As generally used in the art, an electrical terminal exists when something movable is connected to something stationary, while an electrical connection exists when something movable is connected to something else movable, or even when something stationary is connected to something stationary.
The initially described electrical terminal or connector is used to bring a contact element into electrically conductive contact with a mating contact element. The electric terminal or connection therefore interacts functionally with a mating contact element. Correspondingly, the geometry of the mating contact element must be matched to the geometry of the contact element, especially the geometry of the contact zone, so that contact can be made between the contact element and the mating contact element.
Good electrical terminal or connector are typically characterized mainly in that in the contact-making state, the contact resistance between the contact element and the mating contact element is low and also has a permanently constant contact force.
In electrical terminals or connectors of the type under consideration, the contact resistance between the contact element and the mating contact element, which mates with the contact element, is dependent on various factors including the geometry of the contact element and the mating contact element, the materials of the contact element and the mating contact element, and especially on the contact force or the contact pressure between the contact element and the mating contact element. The contact force or the contact pressure is generally achieved by the fact that when contact is made, the contact element is elastically deformed so that from the elastic deformation, a reset force is the contact force which results in a corresponding contact pressure. In other words, the electrical terminal or connector are made such that the contact element acts as a spring element.
One problem is that when using a good conductor for the contact element, the spring constant of the contact element is relative low so that sufficient and permanent contact force cannot be accomplished solely by the contact element. This disadvantage is eliminated in the prior art by an additional spring element of spring steel which serves as an overspring for increasing the contact force. The spring element extends over the contact element, especially the bent spring area of the contact element. In the known electrical terminals or connectors, the spring element is matched in its geometry to the geometry of the contact element. In addition, with reference to the contact element and the contact zone, the spring element is located on the outside, so that the spring force of the additional spring element acts in addition to the existing spring force of the contact element. Such electrical terminal or connector with an additional spring element that provides overspring has the advantage that the contact element itself can be produced from a material with good conductivity, while the high contact pressure which is likewise necessary for good contact is accomplished essentially by the additional spring element.
Electrical terminal or connector of the type under consideration are often inserted into terminal blocks for PE tapping, or in general as flat connectors, conductor bars or the corresponding flat connectors being used as the mating contact element. Due to miniaturization of the terminal blocks, increasingly less space is available for the electrical terminal or connectors. Therefore, both the contact element and also the additional spring element being used as the overspring are made as flat metal parts with only a very low thickness. This however, leads to the spring force of the contact element being exposed to bending stress, and also leads the additional spring element to be exposed to bending stress.
The primary object of this invention is to provide an electrical connector or terminal of the above described type in which the contact force is further increased in a very simple and economical manner.
The primary object of the invention is attained in accordance with the present invention by providing an additional spring element which is arranged to the contact element such that the stretching of the additional spring element in the direction of the contact force is greater than the stretching perpendicular to the direction of the contact force.
It was stated above that the contact force between the contact element and the mating contact element is achieved in that when contact is made, the contact element is elastically deformed so that a reset force provides the contact force which exerts a corresponding contact pressure stemming from the elastic deformation. The elastic deformation then results from the fact that when a mating contact element is inserted into the contact zone, the contact legs are pressed apart, especially the spring area of the contact element being subjected to bending stress. Therefore, the direction of stress of the contact element acts in an opposite direction to the contact force. Thus, the arrangement of the additional spring element to the contact element can also be described such that the stretching of the additional spring element in the direction of stress is greater than the stretching perpendicular to the direction of stress. The stretching of the additional spring element relates to the cross section so that on the one hand, stretching means thickness of the additional spring element, and on the other hand, the width of the additional spring element.
Due to the execution and arrangement of the additional spring element in accordance with the present invention, the spring element has a much higher spring stiffness in the direction of stress than the oversprings known from the prior art. Like the electrical terminal or connectors known in the prior art, the contact force of the electrical terminal or connector of the present invention is accomplished essentially by the additional spring element which provides the high contact pressure necessary for good contact between the contact element and the mating contact element.
Despite the increase of the contact force, the electrical terminal or connector in accordance with the present invention can be produced easily and thus economically, and both the contact element and also the additional spring element can be produced, for example, simply by punching out and bending.
According to one preferred embodiment of the present invention, the contact element has a recess or a slot in the lengthwise direction and the additional spring element is inserted into the recess or the slot. In this way, the electrical connector or terminal have especially small dimensions since the thickness of the contact element is only slightly increased when the additional spring element is inserted into the slot. The additional spring element can be made advantageously as a retaining ring which has been deformed in an oblong manner, or especially as a SEEGER(copyright) circlip ring (a type of retaining ring manufactured by Seeger-Orbis Gmbh Company, Germany and the nature of which is defined by German standard DIN 471) which is deformed in an oblong manner. Here, the retaining ring or the SEEGER(copyright) circlip ring is deformed in an oblong manner to the extent that the contact element is made not annular, but rather, is made rectangular.
According to another advantageous embodiment of the present invention, the ends of the contact legs of the contact element are bent in the shape of a wedge or triangle into the contact zone and advantageously, the ends of the legs of the additional spring element are made likewise wedge-shaped or triangular corresponding to the ends of the contact legs. The position of the contact zone is established by the ends of the contact legs which are bent into the contact zone in a wedge shape or triangular shape, and the contact zone is shifted somewhat into the interior of the contact element thereby facilitating the insertion of the mating contact element into the contact element. In addition, due to the ends of the contact legs being bent inwardly in a wedge-shape or triangular shape, recesses on the outside of the contact legs are formed which can be used to attach the additional spring element to the contact element. To do this, the ends of the legs of the additional spring element are likewise made wedge-shaped or triangular so that they can fit into the recesses.
These and other advantages and features of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention when viewed in conjunction with the accompanying drawings.